In general, when a desired semiconductor device is manufactured, a semiconductor substrate is repeatedly subjected to various heat treatments such as a film forming process, a pattern etching process, an oxidation/diffusion process, a quality modification process, an annealing process and the like on the semiconductor substrate. Along with a recent trend toward a high density, a multilayered structure and high integration of semiconductor devices, requirements on device have been increasingly stricter. In particular, in-plane uniformity improvement in heat treatment on a semiconductor substrate and process quality improvement are strongly required.
For example, when a channel layer of a transistor as a semiconductor device is processed, it is typical to perform an annealing process after implanting ions of impurity atoms into the channel layer in order to activate the impurity atoms.
In this case, if the annealing process is performed for a long period of time, the atomic structure becomes stable. However, the impurity atoms are diffused deeply into a film to thereby pass through the channel layer downward. Therefore, the annealing process needs to be performed for a shortest possible period of time. In other words, in order to stabilize the atomic structure while preventing the impurity atoms from passing through the channel layer having a thin film thickness, it is necessary to rapidly increase a temperature of a semiconductor substrate to a high temperature. Further, after the annealing process, it is necessary to rapidly decrease the temperature thereof to a low temperature at which the diffusion does not occur.
In particular, recently, a transistor device having a structure in which an ultra shallow region such as a source-drain extension region or the like is provided in a channel layer has been suggested. In order to maintain electrical characteristics in the shallow region, it is required for the impurity atoms to be activated without being diffused by applying the rapid increase and decrease in temperature.
In order to achieve the above-described annealing process, a lamp annealing apparatus using a heating lamp (see, e.g., U.S. Pat. No. 5,689,614) and a heat treatment apparatus using an LED device or a laser device (see, e.g., Japanese Patent Application Publication Nos. 2004-296245 and 2004-134674, and U.S. Pat. No. 6,818,864) have been proposed.
However, as well known, in a manufacturing process of a semiconductor integrated circuit, various different materials are disposed on a surface of a semiconductor substrate.
For example, during a transistor manufacturing process, various materials having different optical characteristics, such as a silicon oxide film, e.g., SiO2 film or the like, serving as an insulating film, a polysilicon film, a Cu film or an Al film serving as a wiring layer, a TiN film serving as a barrier film and the like, are distributed on the surface of the semiconductor substrate. In this case, various materials have different optical characteristics, e.g., reflectivity, absorptivity, transmittivity and the like, with respect to light, i.e., a visible ray or ultraviolet light used in the above annealing process. Accordingly, the amount of absorption energy varies depending on types of materials. Due to the differences in the optical characteristics, the annealing process may be hardly performed or may not be uniformly performed.
To that end, a heating apparatus for heating a semiconductor substrate by dielectric heating or induction heating by using an electromagnetic wave, such as a microwave, a high frequency wave or the like, of which wavelength is longer than those of visible ray and ultraviolet light has been proposed (see, e.g., Japanese Patent Application Publication Nos. H5-21420, 2002-280380, 2005-268624 and 2007-258286).
Since, however, each of the aforementioned processing apparatuses is configured as a single-wafer processing apparatus for processing semiconductor substrates one at a time, a throughput cannot be improved sufficiently. Further, when a millimeter wave having a wavelength ranging from a several millimeter to several tens of millimeters is applied as an electromagnetic wave, the amount of the reflected waves from the processing chamber becomes large and the electromagnetic wave source may be damaged if the amount of the electromagnetic waves that can be absorbed by a member to be heated in the processing chamber, i.e., the load absorption capacity (load capacity), is small. In order to avoid this problems, the apparatus needs to have an interlock function for stopping the operation of the electromagnetic wave source in case of generation of an excessive amount of reflected waves, and this leads to the increase of the apparatus cost.